Inspection of a pipeline can sometimes be performed using a system, commonly referred to as a pipeline inspection gauge or “PIG,” which travels inside the pipeline. As an example, a PIG can include one or more sensor modules having sensors arranged for measuring or detecting wall thickness or defects in the wall of the pipeline.
In some instances, the sensors (e.g., ultrasonic sensors, magnetic sensors, etc.) can be mounted on sensor holders of the sensor module(s). The sensor holders can be configured to position the sensors adjacent to the pipe wall at a set inclination angle when, for example, the sensor module(s) carries out an inspection run through a pipeline. These sensor holders can include skids formed of flexible material (e.g., an elastomer). The skids can often be arranged left and right of the sensors, front and back of the sensors, or both. A skid can be configured to run immediately adjacent to or in contact with an inner surface of the pipe, with the sensors arranged at a standoff distance from the outer surface of the skid, in order to protect the sensors against wear or other damage from contact with the pipe and set a given standoff distance. Further, the flexibility of the skid can allow a sensor holder to travel through bends and other pipeline features.